ST PETERSBURG TIMES (Florida) 15 September 03 Champion chomps - Kent Vliet has the tricky job of measuring the bite force of gators. What he learned won't surprise generations of hapless turtles. (Jeff Klinkenberg)
Photo: Alligators have among the strongest jaws in the animal kingdom, a fact not lost on Kent Vliet, a University of Florida researcher who studied the bite force of alligators. In this 1989 photo, Vliet takes a blood sample from a rather toothy specimen. (University of Florida)
Gainesville: Kent Vliet, featured guest at many an alligator banquet, still enjoys wading into murky ponds. Often he carries a sturdy pole and a stout rope. When he nudges something that nudges back, he knows he is in business.
"It's very exhilarating working with alligators," he says.
A University of Florida researcher, he specializes in alligator behavior - and keeping body parts, sometimes unsuccessfully, out of their mouths. His studies have included watching alligators while they fight, court and have sex. More likely than not, he does his watching from the water, often while swimming among alligators.
His latest project required catching some rather robust specimens. Then he induced them to open wide. Only then could another scientist lay an electronic instrument known as a "bite bar" across the big teeth.
Wham!
Keep your hands inside the boat. Vliet and colleagues Greg Erickson from Florida State University and Kristopher Lappin from Northern Arizona University discovered that the American alligator has the most powerful known bite in the animal kingdom.
"They don't fool around," Vliet says. "Sometimes they bite so hard their teeth go flying."
Mike Tyson weighs in
Ever been bitten by an enraged child? It hurts, but at least it isn't as bad as being chomped by, say, Mike Tyson. The maximum bite force from a human, according to the researchers, is a nasty 170 pounds. Humans actually have more imposing choppers than even certain breeds of dogs. For example, a Labrador retriever bites with 125 pounds of pressure.
Most of us who swim in the gulf have nightmares about encountering sharks. A good-sized dusky shark puts 300 pounds behind its bite. In Africa, stay in camp at night: A lion has a bite force of 940 pounds. During the day, avoid stealing carrion from a hungry hyena. They bite with 1,000 pounds of bad attitude.
But the alligator, a living dinosaur, is the most fearsome cookie in that box of animal crackers. At St. Augustine's Alligator Farm, Vliet waded into a pond and dragged a 121/2-footer to his testing table. The excitement must have made Hercules - that's the reptile's name - a tad cranky.
The bite bar was lucky to survive Hercules' indignation.
Imagine a 9-foot grand piano on your foot. Now imagine two Steinways on your foot at the same time. That's what a serious bite from Hercules would feel like. He mauled the bite bar with 2,125 pounds of jaw pressure.
"The hard part was getting him to let go," Vliet says. "Once a big alligator bites, it likes to hang on."
Real Crocodile Hunter
On TV, reptile men are usually kind of flashy. The Crocodile Hunter has that Aussie accent and a born ham's flair for self-promotion going for him. That other TV guy, Jeff Corwin, speaks in a fake German accent as he chases bewildered lizards through assorted swamps.
That's show biz for you. The real crocodile hunter is 46, bald and slightly overweight. Like the TV guys, Kent Vliet carries a big stick. But he talks softly.
He was born in Oklahoma, far from crocodilian country though in the heart of the rattlesnake belt. At the University of Oklahoma he studied herpetology before moving to Gainesville for a graduate degree. Not content to sit at a desk, he did most of his field work submerged on the way to his doctorate.
"The first time I ever swam with them I made a mistake," he says. "I went in first thing in the morning when alligators are more active and a little testy. A big boy swam right up to me. I stood up with my stick and stopped the attack."
Alligators taught him humility. He found he could enter the pond at the alligator farm if he minded his manners and got to know who was boss.
"Alligators are curious animals. Anything novel they want to explore. They don't see that well, so the way they find out about each other or about you is by feel. If they bump you, and you bounce away, they know you're smaller and might be something to eat. But if you push them with some force, they'll think you're a little bigger."
Vliet risked entering the water because he wanted a gator's eye view of their world. He also wanted to understand the alligator's version of a single's bar. Prospective mates, he found out, communicate their desire by body posture and by touching each other gently with their snouts. Copulation is achieved by positioning tails and exposing genitals. Vliet had to be careful not to blink. The whole sex act is over in 30 seconds.
Alligators express themselves in other ways. They bellow - a deep voice from the age of dinosaurs - and sometimes merely vibrate. The infrasonic signal, inaudible to human ears, is nevertheless so powerful that tiny water particles are shaken off the animal's exposed torso in a fine mist. To Vliet, it is beautiful. To an alligator, the message is, "Don't mess with me."
Much of their communication - Vliet has learned to talk alligator - has to do with body posture. When an alligator puffs up, rises high in the water and shows off the length of its torso, it is time to surrender the swimming hole. The gator likely is poised for an attack.
"After a while I learned to read the alligators," Vliet says.
One exception was the sneaky fellow that never played by the rules.
"When an alligator attacks, it typically stays on the surface of the water until the very last second. But this one would swim across the pond underwater. I'd see him coming and put my stick in front of him. He'd open his jaws and try to come around the stick to get me. Not once, but he did it three times. He got me only once, on the calf. It was what I call a mock bite. He wasn't trying to eat me, but to give me a message."
No matter. Enough was enough. Next time, Vliet waded into the pond, charged the bad boy and dragged him to land. He tied the alligator to a tree. Five straight mornings he tied the alligator to the tree. On the sixth morning, the alligator automatically fled to the far side of the pond. Lesson learned.
Vliet has captured hundreds of alligators during his career. His technique is to grab the gator by the tail and work his way up the body. Eventually he likes to ride the alligator like a cowboy rides a horse. While astride the gator he tosses a loop around its jaws.
It usually works. One time a big alligator took him for a ride into the pond.
In the deepest part, it suddenly dove and Vliet found himself in the middle of an alligator bacchanalia. Lunging, a big one sliced his wrist open to the tendons. "It took a long time for sensations to come back to my hand," he says. "I'd be in a convenience store, with my hand out, waiting for my change for some purchase. Then I'd look up and see that they'd already given me my change - I just couldn't feel it. I felt kind of stupid standing there with my hand out."
How to annoy a gator
Alligators ambush prey. Some victims - fish or small mammals - are gulped down like popcorn. Alligators typically drown larger prey and shake them apart. Then they wolf down the bite-sized pieces. Powerful jaws come in handy when eating rock-hard turtles.
During the bite-pressure study, Vliet's job was subduing the animal. He'd straddle the back, reach forward and release the rope keeping the jaws shut. Then he'd tap the alligator on the back of the skull until, out of irritation, it opened up. A colleague would then present the bite bar.
Made from surgical steel, the bite bar was 7 feet long. At the end were four electric sensors sandwiched between two flat plates. When the gator crushed the plates together, the scientists got their measurement.
That was half the battle. The other half was getting the bar back. "Sometimes they just don't want to give it back," Vliet says. "You have to wait or keep pulling at it. We bent our bars." Paid for by the UF, FSU and the National Geographic Society, the three bars cost a total of $15,000.
The study isn't over. Vliet next plans to measure the biting force of wild alligators. He's curious whether their jaws will be stronger or weaker than captive animals. Captive alligators usually eat soft food and weigh more. They spend more of their lives basking out of the water; gravity can change the skull structure. Wild alligators eat harder food, especially turtles. Their skulls tend to be more streamlined.
The third part of the study will involve measuring the bites of crocodiles. Crocs generally have more narrow snouts evolved for grasping fish. Of course, there are exceptions. Crocs from Africa and Australia are confirmed eaters of large animals and even humans.
Australian crocodiles can attain 20 feet in length. They are the direct link to Sarcosuchus imperator, which roamed Africa 140-million years ago. Paleontologists believe they grew to 40 feet and ate dinosaurs. Extrapolating bite measurements from alligators, Vliet and colleagues believe the ancient crocodile bit with 18,000 pounds of pressure - roughly the weight of a Mack truck.
The largest alligator Vliet ever saw was a husky specimen that hung around the boat ramp at a park in the Okefenokee Swamp in Georgia. One morning it was on the bank, asleep. Vliet got the idea of sneaking up on it and using a broom as a crude measuring stick.
Everything was going smoothly until he slipped on the wet grass.
"Next thing you know, I'm whacking him over the head with the broom stick as I try to scramble to my feet. He wakes up, almost explodes into movement. As I scurried over the fence, he crashed into the water. I'm sure he was a 14-footer." - Jeff Klinkenberg's phone number is 727 893-8727. His e-mail address is klink@sptimes.com
For more about alligators and crocodiles, The University of Florida's Natural History Museum Web site is http://www.flmnh.ufl.edu/natsci/herpetology/brittoncrocs/cnhc.html
Tale of the teeth
A comparison of bite force among predators, including humans:
Tyrannosaurus rex Maximum bite: 3,011 pounds
American alligator: Maximum bite: 2125 pounds
African lion Maximum bite: 940 pounds
Dusky shark Maximum bite: 300 pounds
Human Maximum bite: 170 pounds
Source: University of Florida and University of California, Berkeley (Tyrannosaurus rex)
Kent Vliet has the tricky job of measuring the bite force of gators.